The wsmux is a pseudo-device driver that
allows several wscons(4) input
devices to have their events multiplexed into one stream.

The typical usage for this device is to have two multiplexors, one for mouse
events and one for keyboard events. All
wsmouse(4) devices should
direct their events to the mouse mux (normally 0) and all keyboard devices,
except the console, should direct their events to the keyboard mux (normally
1). A device will send its events to the mux indicated by the
mux locator. If none is given the device will
not use a multiplexor. The keyboard multiplexor should be connected to the
display, using the
wsconscfg(8) command. It will
then receive all keystrokes from all keyboards and, furthermore, keyboards can
be dynamically attached and detached without further user interaction. In a
similar way, the window system will open the mouse multiplexor and receive all
mouse events; mice can also be dynamically attached and detached.

It is also possible to inject events into a multiplexor from a user program.
This is used by the
wsmoused(8) daemon to take
data from a mouse connected to a serial port and make it appear on the
standard mouse mux.